THE PROLIFERATIVE ACTIVITY OF ASTROCYTES AFTER IMMUNOGLOBULIN-G UPTAKE IN THE INJURED MOUSE CEREBRAL HEMISPHERE

Dividing cells were labeled with [H-3]thymidine injected at different intervals following the injury of the rat cerebral hemisphere. Brain s ections were double immunostained for GFAP and for immunoglobulin G (I gG), and subjected to autoradiography. Thereafter, three cell types we re counted within the injury area: (1) autoradiographically labeled an d (2) unlabeled astrocytes immunopositive both for GFAP and IgG (GFAP/IgG-), and (3) autoradiographically labeled astrocytes immunopositive exclusively for GFAP (GFAP+/IgG-). Reactive proliferation of GFAP+/Ig G- astrocytes began on the Ist day after injury and reached its maxima l intensity on day 4, whereas the population of non-proliferating GFAP +/IgG+ astrocytes increased continuously during 8 days after injury an d then decreased. Proliferating GFAP+/IgG+ astrocytes were found only occasionally during the whole examined period and did not-display sign ificant quantitative changes. The results suggest that the ability of astrocytes to proliferate after IgG uptake is very low in comparison w ith those containing no IgG.